Question

Vitamin C is a water-soluble vitamin, so your body doesn't store it. You have to get the required amount from your diet (citrus fruits are a great source!), or you could take a daily vitamin C supplement pill. Vitamin C is ascorbic acid, so to determine how much vitamin C (acid) has been placed in each pill, you could do an acid-base titration. One vitamin C pill was dissolved in water and titrated to an endpoint by 16.00 mL of a 0.447 M solution of NaOH. How many grams of ascorbic acid were there in the pill? (MW of ascorbic acid is 176.1 /mol). Explain and show your work.​

Answer 1

The pill contained approximately 1.259 grams of ascorbic acid, determined by an acid-base titration with sodium hydroxide.

Step-by-step explanation:

To determine how many grams of ascorbic acid were in the pill, we'll use the principles of acid-base titration. The titration's endpoint indicates that the amount of base added neutralized the acid in the pill. The reaction between ascorbic acid (C6H8O6) and sodium hydroxide (NaOH) is as follows:

C6H8O6 + NaOH → NaC6H7O6 + H2O

Each mole of ascorbic acid reacts with one mole of NaOH. From the titration data, we have:

Volume of NaOH = 16.00 mL (0.016 L)

Molarity of NaOH = 0.447 M

The moles of NaOH that reacted with the ascorbic acid:

moles NaOH = Molarity × Volume = 0.447 mol/L × 0.016 L = 0.007152 mol

As the molar ratio of ascorbic acid to NaOH is 1:1, the moles of ascorbic acid are also 0.007152 mol. To find the mass of ascorbic acid:

Mass of ascorbic acid = moles × molecular weight (MW)

Mass = 0.007152 mol × 176.1 g/mol

Mass = 1.259 g (rounded to three significant digits)

Therefore, the pill contained approximately 1.259 grams of ascorbic acid.

Answer 2

Mass of ascorbic acid in the pill = 7.152 x 176.1/1000 = 1.26 g

Step-by-step explanation:

The mass of ascorbic acid in the pill would be,

1.26 g

Now,

Moles of ascorbic acid = Moles of NaOH = 0.447 M x 16 ml = 7.152 mmol

Mass of ascorbic acid in the pill = 7.152 x 176.1/1000 = 1.26 g